The present invention relates to systems for monitoring the entities of a communication network through continuous collection and analysis of data derived by observing their performance. More particularly, the invention relates to a system and a method for monitoring the performance of the lines in a digital communication network.
There are a variety of strategies governing maintenance operations associated with today""s telecommunications networks. While maintenance strategies are fairly diverse in their procedural details, they are usually based upon a common set of guiding principles (or philosophies) that are intended to fulfill the general needs and objectives of individual network providers. Maintenance strategies rely upon three fundamental operations tools: Surveillance, Testing and Restoration.
Surveillance refers to the real-time, non-intrusive monitoring of the various components of a network, so that performance degradations can be identified before customer service is adversely affected.
The surveillance is principally performed by the performance monitoring which is defined in the American National Standard for Telecommunications xe2x80x9cLayer 1 In-Service Digital Transmission Performance Monitoringxe2x80x9d as being the monitoring of a particular entity""s health through continuous collection and analysis of data derived by observing its performance. In the context of this standard, the term performance monitoring refers to the set of functions and capabilities necessary for a network element to gather, store, threshold and report performance data associated with its monitored digital transmission entities. These performance-related data elements are termed performance parameters.
When applied to lines as entities of the network, the performance monitoring relates to all digital line communications for line speeds starting from 1.544 Mbps (T1) up to 155 Mbps (OC3) and above.
Line performance monitoring relies on a set of performance counters which is defined for each digital line. These counters are capital for services that do not define any other performance counters such as voice. They are also important for digital data, for instance HDLC.
At each node of a communication network to be monitored, a line interface includes several successive hardware elements such as a front end transformer, a line transceiver and a framer. Usually, a processor is in charge of configuring the hardware elements and also managing alarms and line performance parameters. So, the processor collects the defects and anomalies and generates performance counters by running a specific software process.
Such a line performance monitoring presents several drawbacks. First, it is timing dependent insofar as several counters require a complex timing adjustment as, for example, for the parameters depending on the failures.
This line performance monitoring is also totally dependent on hardware. As a matter of fact, assuming a T1 interface is replaced by an E1 interface, the framer has to be changed and therefore, all register addresses and contents enabling to process line performance parameters are different.
Furthermore, the high number of line performance parameters increases the technical complexity since the total code length is usually proportional to the number of parameters which are monitored by counters. This number which can be very important increases the complexity, as for example in SONET requiring 49 such counters.
It is why the object of the invention is to provide a new system and process of line performance monitoring using a software process which is independent on hardware and timing.
To achieve the foregoing object, the invention relates to a system for monitoring the performance of at least one line at a node of a digital communication network, such a system including a set of hardware registers associated with the line for registering line performance information associated therewith, a set of counters associated with the line, each counter defining a parameter depending on the line performance information, and a processing unit for, during a predetermined period of time, gathering the line performance information from the hardware registers, computing the parameter and writing the parameters defined by the counters in a performance report to be sent to a network management unit. The system also comprises one table associated with each line for storing all the data necessary to read the parameter for each counter of the set of counters associated with this line, and a processing machine for reading the table, sequentially computing the parameters defined by each counter by using the data stored in the table, and sequentially updating the counters.
Another aspect of the invention is a process of monitoring the performance of at least one line at a node of a digital communication network using the above system comprising the steps of reading from a sub-table of the table associated to a counter to be updated, the data necessary to read performance information on the line from the associated hardware registers and to compute the parameter for this counter, reading the hardware registers by using a first part of the data read in the sub-table, computing the parameter for this counter by using a second part of the data read in the sub-table, updating the counter by the computed parameter, and writing this parameter in the performance report to be sent to the network management unit.
The objects, features and advantages of the invention will be more readily understood in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic diagram representing a digital communication network wherein the invention can be implemented.
FIG. 2 is a block-diagram of a card interfacing a communication line in a node of a network illustrated in FIG. 1.
FIG. 3 is a flow-chart of the processing machine incorporated in a system according to the invention.
FIG. 4 is a schematic representation of the essential features used in a system according to the invention.
FIG. 5 is a diagram representing the total code length with respect to the number of interfaces without using the invention and with the use of the invention.